[t/spec] skip a passing TODO test that is likely a false positive

git-svn-id: http://svn.pugscode.org/pugs@30261 c213334d-75ef-0310-aa23-eaa082d1ae64

S32-array/exists.t

@@ -21,7 +21,7 @@ ok @array.exists(2),    "exists(positive index) on arrays (3)";
 ok @array.exists(3),    "exists(positive index) on arrays (4)";
 ok !@array.exists(4),   "exists(positive index) on arrays (5)";
 ok !@array.exists(42),  "exists(positive index) on arrays (2)";
-#?rakudo todo 'negative array indexes'
+#?rakudo skip 'negative array indexes'
 ok !@array.exists(-1),   "exists(negative index) on arrays (1)";
 #?rakudo 6 skip 'Pm wants spec clarification'
 ok @array.exists(*-1),   "exists(negative index) on arrays (1)";